Absorption unit for air compressors



`lune 19, 1951 R. H. HILL v 2,557,431

ABsoRPTIoN UNIT FOR AIR' coMPREssoRs original Filed Dec. 22, 1945 JNVENTOR. Roaman/. ,7K/LL,

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Patented June 19, 1951 ABSORPTION UNIT FOR AIB COMPRESSORS Robert H. Hill, Fort Wayne,` Ind., assignor to Tokheim Oil Tank and Pump Company, Fort Wayne, Ind., a corporation of Indiana Original application December 22, 1945, Serial No. 636,864. Divided and this application October 7, 1949, Serial No. 122,662

2 Claims. (Cl. 230-22) This invention relates to a positive displacement air compressor, particularly to an absorption unit for such an air compressor and a discharge fitting for the absorption unit. This application is a division of my prior application Serial No. 636.864, filed December 22, 1945.

The object of the invention is to produce a simple, compact air compressor which will operate quietly and efllcently at a. relatively high compressor speed to deliver airawith low pulsation, which compressor may be mounted on and direct connected to a standard electric motor, to form a readily portable unit.

My absorption unit may be associated with a compressor comprising a crank case mounted directly on the end of a standard electric motor, with the compressor head mounted on that crank case. A cylinder is formed in the head, and a piston is reciprocated therein through a rod driven by an eccentric crank on the shaft of the electric motor.

The relatively high speed of the compressor delivers air with minimum pulsation, but preferably I form an absorption chamber in the compressor base, and deliver air therefrom through a fitting which also embodies an overload relief valve and a manual relief and clean-out valve.

The accompanying drawing illustrates my invention. In such drawing: Fig. 1 is an end elevation of a compressor embodying my invention; and Fig. 2 is a side elevation of the compressor shown in Fig. 1, with the crank case, head, and outlet fitting shown in section.

The compressor is shown in the drawings as associated with an electric motor I0. 'Ihe crank case II of the compressor is mounted directly on the end of the motor I0, and the compressor head I2 is mounted on the crank case I I.

An eccentric I5 is mounted on the shaft I6 of the motor I0, conveniently by a key I1 locked in the key wayof the shaft I6 by a set screw I8. The big end of the connecting rod is mounted on the eccentric I5. preferably by needle bearings 2l, and isheld against axial movement by counterweight disks 22 attached against the sides of the eccentric I5 as by bolts 23. The small end of the connecting rod 20 is connected to the piston by a sleeve bearing and a piston pin 26. Desirably, the piston pin 26 is locked to the piston by a cross pin 21.

The piston is formed of a carrier and a head 30. 'I'he carrier extends upwardly to form a hollow guide rod 28 slidabie in a central guide bore in the head I2. The piston head 30 is mounted on the carrier 25, desirably by locking it against a suitable shoulder with a lock nut 3| which is pinned in locked position. The piston head 30 is relatively short, with its side walls of suillcient length to form a ring band and some bearingsurface against the cylinder 35, but with substantially no skirt. The use of the guide 28 fully prevents piston wobble without the necessity for any extended skirt on the piston. This permits the piston and cylinder to be short so that the cylinder can conveniently be formed in the head; and reduces theweight of the moving parts to facilitate operation at the relatively high speed (for a compressor) of a standard electricmotor III.

An intake passage 31 is formed in the head, and to receive one end of an intake tube 38. The passage 31 is shouldered so that a filter screen 39 may be received between the shoulder and the inner end of the inlet tube 38. Desirably, the screen 39 is formed of two layers of wire mesh, with an intervening layer of felt. An additional screen 40 may be placed in the open end of the tube 38, and if desired the tube 38 may contain silencing material, but I have found that the compressor operates with remarkable quietness without the necessity for any such silencing material. The outer end of the tube 38 is secured to the motor III, as by a bracket 4I, so that the tube may serve as a handle for transporting the compressor.

The intake passage 31 leads to a pair of intake valves. An outlet passage 51 leads from a pair of outlet valves, and is connected to a pipe 58.

A vent passage 42, drilled in the crank case and head, leads from the crank case to communication with the intake passage just outside the screen 39. A seat for a valve in this vent passage 42 is formed in a chamber 43 in the upper surface of the crank case, and a disk valve 44 is positioned in the valve chamber 43 against the seat when the compressor is assembled. The head of a. screw in the lower surface of the head "I2 overlies the valve disk 44 to limit its displacement.

The valved crank-case vent maintains the case under slight vacuum and leads normally escaping oil vapor to the intake, to moisten the lter screen 39. Such oil vapor also supplements the splash system of lubrication, especially when high pressure operation tends to dry the cylinder walls, for under those conditions oil-vapor escape tends to increase, and this is delivered through the intake for top-cylinder lubrication.

The compressor is carried by a base 60, preferably by mounting the motor I0 on a suitable bracket 6I on that base 60. The base 80 is 3 formed to provide an absorbing chamber 65. to which the pipe il leading from the outlet passage 51 of the compressor is connected.

The compressed air is delivered from the ab sorbing chamber i5 through an outlet connection I6 of a fitting 10, which also houses an overload relief valve and a clean-out and manualrelief valve. The over-load relief valve is formed in a boss 13 on the fitting 10. It has a plunger 12 spring-pressed inwardly to urge its bluntly tapered inner end against a seat formed in the fitting 10, to normally close a passage 14 which is in open communication with the absorbing chamber 8l.

A clean out tube 15 leads from near the bottom wall 84 of the absorbing chamber 85 upwardly through the fitting out of communication with the normal air delivery passage, to a valve 1S which is normally held in closed position by the spring 11. A head on the stem of the valve 16 may be manually depressed to open the valve and release air through the clean-out tube 15 to a relief opening 18. Normal operation of the relife valve 16, as when starting the compressor. will automatically give clean-out action to remove any accumulation of moisture and oil condensation.

My compressor may be direct connected through the connection 6l to a device requiring compressed air, such for instance as a spray gun, a grease gun, etc.

The design of my compressor, and the low weight of its moving parts, contribute to make it operate quietly and efficiently at high speed, as at the standard high speed of the electric motor I0, or even at substantially higher speed. Oil vapor unavoidably escaping from the crank case is carried by the vent-passage to the intake and utilized to moisten the filter and for top lubrication,

especially when operation at high pressures tends 0 1,923,127

to reduce normal top-cylinder lubrication. Air delivery is smooth and prompt, to provide air at high pressure, or in greater quantities at lower pressure, as its use may require.

I claim as my invention:

1. In combination with an air compressor, an absorption chamber through which air delivery occurs, a delivery fitting secured to said absorption chamber, an open passage through said fitting for air delivery, a side-passage communicating with said delivery passage, a relief valve normally closing said side-passage, a second side passage, a conduit in communication with said absorption chamber near the bottom thereof, said second side-passage being connected to said conduit and cut oil from communication with said delivery passage, and a manually operable relief valve closing said second side-passage.

2. In combination with an air compressor, an absorption chamber through which air delivery occurs, a delivery fitting secured to said absorption chamber, an open passage through said fitting for air delivery, a side-passage, a conduit in communication with said absorption chamber near the bottom thereof, said side-passage being connected to said conduit and cut'off from communication with said delivery passage, and a manually operable relief valve closing said sidepassage.

ROBERT H. HILL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,630,741 Grimths May 3l, 1927 1,802,175 Hobart Apr. 21, 1931 Veenschoten Aug. 22, 1933 

